Research On Electrode/Electrolyte Interface Design Of All Solid-state Lithium And Magnesium Batteries

The performance of traditional lithium-ion batteries is close to its theoretical value.Metal electrodes such as lithium and magnesium have the advantage of high specific capacity.Batteries based on such metal anodes are expected to become high-energy-density battery systems,but the uncontrolled growth of metal dendrites and the use of organic electrolytes have unavoidable safety problem.Therefore,the development of next-generation solid / quasi-solid metal batteries with high energy density and high safety performance is one of the future trends.One of the important challenges of this type of battery is how to solve the interface problem between the metal negative electrode and the solid electrolyte.Among them,lithium metal batteries have challenges such as poor contact between the lithium metal and solid electrolyte interface,and uncontrolled growth of lithium dendrites.Magnesium batteries also suffer from poor contact between the magnesium metal and the solid-state electrolyte.In addition,the unique reactivity of magnesium metal is also prone to high interface resistance.Therefore,a reasonable interface design between the metal negative electrode and the solid electrolyte is the key to preparing a high-performance solid / quasi-solid metal battery.This research paper first focuses on the interface between the lithium metal anode and the solid electrolyte.A new type of PIN @ SN "glue" electrolyte was synthesized.The electrolyte has good ionic conductivity(1.5 × 10^-4S / cm at room temperature),interface wettability?wettable to common electrode materials and solid electrolytes?,and excellent electrochemical stability?electrochemical window is 4.6V?.It also has good adhesion?peel strength of 70¹90 N/cm?.Therefore,using the "pre-polymerization-post-curing" strategy to modify this "glue" between the interfaces can solve the interface contact problem between the electrode and the inorganic electrolyte?LLZTO?.The results show that the interface resistance of the obtained all-solid-state lithium battery is significantly reduced at room temperature?resistance is reduced from 5114 ? / cm² to 104 ? / cm²?,and stable cycling can be achieved?50 cycles after 0.05 cycles at 0.05 C rate?.95.2% capacity retention rate).Such "glue" electrolytes have the advantages of light weight and high performance,are easy to synthesize and design,and have the potential for large-scale applications.This research paper also carried out related research on the electrode / electrolyte interface of quasi-solid magnesium batteries.In order to solve the interface contact problem between the magnesium metal negative electrode and the solid electrolyte,we use a small amount of electrolyte to wet the interface to achieve a stable cycle in a quasi-solid Mg / Mg symmetrical battery at a large rate.The main research results include:?1?Using polyacrylonitrile to prepare a layer of artificial solid electrolyte interphase?SEI?on the surface of magnesium metal.Studies have shown that this SEI can suppress the interface side reactions of trace electrolyte and magnesium metal.?2?Mg?TFSI?₂/SN electrolyte is used to wet the interface between the magnesium electrode and the solid electrolyte.Studies have shown that the interface impedance of this magnesium battery is reduced from 4612 ? / cm² to 227 ? / cm².?3?Assemble a quasi-solid magnesium symmetrical battery for cycle testing.At a current density of 0.1 mA / cm²,its polarization voltage is only 12 mV,and it remains stable after 1000 h of cycling.This work laid the foundation for the research of solid / quasi-solid magnesium batteries,and also provided ideas for the development of other multivalent ion solid batteries.